A plug-in device, such as an electrical charger, generally includes an insulating housing, a plug and a circuit mounted within the housing. The plug is used to accept power supplied by an external power source and deliver the power to the circuit. The plug of a typical plug-in device has two conducting blades extending from the housing. The actual configuration of the blades depends on the country for which the plug-in device is designed.
One prior art charger with a foldable plug is the charger provided by PALM COMPUTING®. Their charger has a cylindrical housing base, with a circuit board arranged in the housing base. There is a plastic positioner placed on top of the circuit elements. The paired blades are placed on top of the plastic positioner. The paired blades rest on a holder in the plastic positioner. A housing cover, made of the same material as the housing, is then placed over the blades, and the plastic positioner is bonded to the housing cover. The housing cover is then permanently coupled to the housing base. A force is applied to the blades by a bending tab on the plastic positioner, when a user opens or closes the blades, which snaps the blades into the open and closed positions. The blades exert pressure on the plastic holder continuously, whether they are open or closed.
However, this device has a number of drawbacks. First, it has an extra element that needs to be assembled, bonded to the housing cover, in addition to the two housing pieces. This means that manufacturing and assembly tolerances between the separate pieces may cause issues. Second, use introduces significant stress on the bending tab of the plastic positioner, reducing the feel of the opening and closing click. Third, over time the constant force on the bending tab in the open and closed positions will permanently deform the bending tab and further reduce the feel of the opening and closing force.